Diagnostic analysis of veterinary dried blood spots for toxic heavy metals exposure

Dried blood spots (DBS) on filter paper have been used in human medicine since the 1960s, predominantly for screening in-borne metabolic disorders and more recently, for toxicology. Despite its 50-year existence, this technology has not been adopted by veterinarians for routine diagnoses and research. We have validated a novel DBS analytical procedure for the routine measurement of toxic heavy metals using 50 µL of whole blood on a single DBS by inductively coupled plasma mass spectrometry (ICP-MS). Targeted heavy metals are arsenic, cadmium, mercury, lead, selenium and thallium. The limits of quantitation (LOQ) on DBS are: arsenic 1.7 µg/L, cadmium 4.0 µg/L, mercury 13.7 µg/L, lead 13.3 µg/L, selenium 6.3 µg/L and thallium 1.5 µg/L. These LOQs suffice for routine diagnoses of heavy metal intoxication in domesticated and wildlife species as well as for basic, applied and epidemiological studies. The technique is ideal for population studies involving investigations of wildlife exposure to heavy metals and other environmental pollutants. The small blood volume involved (50 µL) makes it feasible to study small animals (birds, reptiles, amphibians and small mammals) that were previously excluded, or difficult to study due to the relatively large sample volumes required by current gold standard blood collection techniques.